In this paper, comet coma sample return mission is discussed and proposed as one of the most promising interplanetary missions in the 1990’s. As the result of preliminary mission analysis, the comet Churyumov-Gerasimenko (C.G.) was selected, out of 36 candidates of short period comet, as the best target to be en-countered with a spacecraft. This selection was done by taking into consideration of assurance of a fair amount of “intact” cometary dust sampling and free earth return trajectory. A typical mission scenario to the comet C.G. shows that the spacecraft should be launched in 1995, will fly by the comet on January, 1996 and will return to the earth in 2000. Aerobraking technique should be used in order to lower apogee height of the orbit around the earth before retrieval by an Orbital Maneuvering Vehicle. The result also shows that a spin-stabilized 500 kg class spacecraft can be sent if a launch vehicle of which capability is about 2 tons to LEO is available.

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A conceptual study on a racer to the moon which is propelled by solar light pressure with solar sail was conducted. The racer was assumed to be carried by a launch vehicle, packed in a cylindrical and to start from an near geosynchronous orbit and finish at a certain destination determined in connection with the moon. A spinning type and a three-axes-control type of spacecraft were designed. Structural and thermal analyses were performed and guidance and control of each spacecraft were studied. As a result, problem areas for design of such a racer were made clear and useful data to determine racing rules to the moon were obtained.

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A solar sail race to the moon is no longer a dream. The launch is scheduled in early 1990’s. But its flight control has several problems to be overcome. One major concern is its sail steering strategy. Even when the sail direction is computed, with various disturbances especially due to the flexible nature of the sail, the actual maneuver using a very faint control torque is extremely difficult. Although the baseline design itself is premature, through carefully examining key parameters and evaluating the control capability, a typical orbital profile is generated, and the feasibility of the race is investigated.

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In the 21st century, development of the lunar surface will be important for three reasons . First, the moon is a suitable base for astronomy, as well as an object of scientific research. Second, lunar resources can be used effectively on the moon and in space . Third, the moon will be an outpost for further exploration of the universe. This paper describes a future Lunar City from the point of view of construction. The conceptual design was made on the assumptions that the Lunar City will be constructed near the south pole and that the city will have a population of 10,000 inhabitants. The construction method for main facilities in the city was also considered. Most of the construction materials, with the exception of water, can be obtained by processing of lunar rocks and soils. Sunlight can be utilized as an energy source by generating electricity with solar panels.

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In the near future, it is expected that the human space activities will extend further, and a lot of citizens will inhabit in space. It seems that the growth of space population will make a space based medical institution necessary. From an architectural viewpoint, a preliminary conceptual design of “a medical center in space” is presented. The construction of this facility would allow not only space dwellers to undergo medical treatment, in the gravitational zone but also earth dwellers to take medical care in the micro-gravitational zone. The facility will be situated in the area where both terrestrial (1 G) and space (0 G) gravitational conditions coexist. Therefore, it can function as an intermediate installation that enables human body to get accustomed to environmental change from 1 G to 0 G and vice versa.

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